The Fruit of Blueberries
The single layered outer epidermis has no stomates and is covered with a cuticle about 5 um thick and a waxy bloom at maturity.
The amount of bloom varies with the cultivar and stage of maturity. Pigments are present in the epidermal and hypodermal layers, which are delineated from the rest of the cortex by a ring of vascular bundles.
The mesocarp is fairly homogenous parenchyma and contains two more rings of vascular bundles.
The carpels contain five large, highly lignified placentas to which up to 65 seeds are attached.
The locules, surrounded by a stoney endocarp, extend into the mesocarp. Stone cells are distributed unevenly throughout the mesocarp, but occur with highest frequency from just blow the epidermis to a depth of about 1.4 mm.
They occur rarely in intercarpellary areas and in sepallary tissue and infrequently in the vascular and in nectariferous tissue.
Mature stone cells usually appear completely vacuolated and have a thick heavily pitted, essentially smooth secondary wall composed of several lamellations, each about 1 um wide.
They are composed mostly of lignin and contain little cellulose. The simple wall pits puts are contagious with pits in adjacent stone cells, or with pit field in adjacent parenchyma walls.
The Fruit of Blueberries
